Using the feasible parameters [1]}, \(\Delta =2\pi \times 2\textmd {MHZ}\) , \(\kappa =2\pi \times 100\textmd {MHZ}\) , and \(g_{13}\approx g_{23}\approx 2\pi \times 10\textmd {MHZ}\) . The gain in magnetic materials can be realized by parametric driving from an ac magnetic field [2]}. A recent experiment has demonstrated that a negative magnetic damping can be induced by the electric field in
heterostructured ferroelectric|ferromagnet layers [3]}. To reduce the experimental difficulty for realizing a
negative magnetic damping, Ref. [4]} proposed a PT-symmetric synthetic electric circuit coupled with a ferromagnetic sphere.
